1. Field of the Invention
The present invention relates to a connector head construction for a high-pressure fuel injection tube which is placed in a fuel supply passage in a diesel engine and has a relatively large wall thickness and small diameters such as an outside diameter of about 20 mm or less and an inside diameter ranging from 1.2 mm to 4 mm.
2. Description of the Prior Art
One conventional connector head construction for use in fuel injection tubes is illustrated in FIG. 2A of the accompanying drawings. A metal tube 11 of a large wall thickness has on a connecting end thereof a connector head 12 in the form of an abacus bead having a front outer peripheral pressor wall 13 and a rear outer peripheral pressure-bearing wall 14. The pressure-bearing wall 14 is defined by a steep slant surface 14' extending from a top portion to a lower neck portion. Another prior connector head construction shown in FIG. 2B includes a sleeve washer 17 fitted over a pressure-bearing wall 14 including a lower neck portion for engagement with a fastening nut 16.
However, the conventional connector head constructions have been disadvantageous in that since the pressure-bearing wall 14 is composed solely of the simple steep slant surface 14', the neck portion of the connector head 12 has an insufficient mechanical strength so that the neck portion will frequently be cracked or broken under engine vibrations during use or undue stresses produced upon forced connection of a product tube which is not bent to proper shape. The same problem arises even with the sleeve washer 17 fitted over the neck portion.